/* Hướng thiết kế: vở ô ly và mực tím của học trò Việt Nam.
   Nền giấy lạnh, chữ mực đen xanh, mực tím làm màu chủ đạo; lưới ô ly chỉ xuất hiện ở bản đồ kỹ năng. */
:root {
  --paper: #F6F7FB; --sheet: #FFFFFF; --ink: #1D2433; --ink-2: #4A5368; --ink-3: #7A8296;
  --violet: #4B2E83; --violet-2: #6C4BB0; --violet-soft: #EFEAF8;
  --rule: #D9DDE8; --grid: #E3E7F1;
  --ok: #1F7A4D; --ok-soft: #E4F3EA; --warn: #9A5B00; --warn-soft: #FBF0DC; --bad: #B42318; --bad-soft: #FBE7E5;
  --font: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, Consolas, "Courier New", monospace;
  --r: 6px;
  --on-primary: #FFFFFF; --on-primary-muted: #E4DAF6;
  --field: #FFFFFF; --editor-bg: #FCFCFE; --code-bg: #F2F3F8; --code-bar: #EEF0F7; --codebox-bg: #F7F8FC; --hl: #E9E4F5;
  --heat-mid: #C9B8EA; --explain-bg: #FFF7E6; --accent-warm: #D08A1E; --add-bg: #E3F4EA; --del-bg: #FBE5E3;
  --accent-2: #D08A1E;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body { background: var(--paper); color: var(--ink); font: 15px/1.6 var(--font); }
a { color: var(--violet); text-underline-offset: 2px; }
a:hover { color: var(--violet-2); }
:focus-visible { outline: 2px solid var(--violet-2); outline-offset: 2px; }
h1 { font-size: 1.6rem; line-height: 1.25; font-weight: 700; margin: 0 0 .25rem; letter-spacing: -.01em; }
h2 { font-size: 1.15rem; font-weight: 650; margin: 0 0 .75rem; }
h3 { font-size: 1rem; font-weight: 650; margin: 1rem 0 .5rem; }
p { margin: 0 0 .75rem; max-width: 72ch; }
.muted { color: var(--ink-3); }
.small { font-size: .86rem; }

/* Khung trang */
.top { background: var(--sheet); border-bottom: 1px solid var(--rule); }
.top .in { max-width: 1240px; margin: 0 auto; padding: .6rem 1.25rem; display: flex; gap: 1.5rem; align-items: center; flex-wrap: wrap; }
.brand { font-weight: 700; color: var(--violet); text-decoration: none; display: flex; align-items: center; gap: .5rem; }
.brand .mark { width: 22px; height: 22px; border: 2px solid var(--violet); border-radius: 4px;
  background: linear-gradient(var(--violet) 0 0) 50% 50%/10px 2px no-repeat, linear-gradient(var(--violet) 0 0) 50% 50%/2px 10px no-repeat; }
.nav { display: flex; gap: 1rem; flex-wrap: wrap; }
.nav a { color: var(--ink-2); text-decoration: none; padding: .2rem 0; border-bottom: 2px solid transparent; }
.nav a.on, .nav a:hover { color: var(--violet); border-bottom-color: var(--violet); }
.who { margin-left: auto; color: var(--ink-3); font-size: .9rem; }
main { max-width: 1240px; margin: 0 auto; padding: 1.5rem 1.25rem 3rem; }
.head { margin-bottom: 1.25rem; }

.panel { background: var(--sheet); border: 1px solid var(--rule); border-radius: var(--r); padding: 1.1rem 1.2rem; margin-bottom: 1.25rem; }
.cols { display: grid; grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); gap: 1.25rem; }
.split { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 6fr); gap: 1.25rem; align-items: start; }
@media (max-width: 900px) { .split { grid-template-columns: 1fr; } }

/* Thông báo */
.flash { padding: .6rem .9rem; border-radius: var(--r); margin-bottom: .75rem; border-left: 4px solid var(--ok); background: var(--ok-soft); }
.flash.err { border-left-color: var(--bad); background: var(--bad-soft); }
.note { background: var(--warn-soft); border-left: 4px solid var(--warn); padding: .6rem .9rem; border-radius: 0 var(--r) var(--r) 0; }

/* Nút, biểu mẫu */
.btn { display: inline-block; font: inherit; font-weight: 600; padding: .45rem .95rem; border-radius: var(--r); border: 1px solid var(--violet);
  background: var(--violet); color: var(--on-primary); cursor: pointer; text-decoration: none; line-height: 1.4; }
.btn:hover { background: var(--violet-2); color: var(--on-primary); }
.btn.ghost { background: transparent; color: var(--violet); }
.btn.ghost:hover { background: var(--violet-soft); }
.btn.quiet { background: transparent; border-color: var(--rule); color: var(--ink-2); font-weight: 500; }
.btn.danger { background: var(--bad); border-color: var(--bad); }
.btn:disabled { opacity: .55; cursor: not-allowed; }
.row { display: flex; gap: .6rem; align-items: center; flex-wrap: wrap; }
label { display: block; font-weight: 600; font-size: .9rem; margin: .6rem 0 .25rem; }
input[type=text], input[type=password], input[type=number], input[type=datetime-local], select, textarea {
  font: inherit; width: 100%; padding: .45rem .6rem; border: 1px solid var(--rule); border-radius: var(--r); background: var(--field); color: var(--ink); }
textarea { resize: vertical; }
.check { display: inline-flex; gap: .35rem; align-items: center; font-weight: 400; margin: .15rem .9rem .15rem 0; }
.inline { display: inline; }

/* Bảng */
table { width: 100%; border-collapse: collapse; font-size: .93rem; }
th, td { text-align: left; padding: .45rem .5rem; border-bottom: 1px solid var(--rule); vertical-align: top; }
th { font-weight: 600; color: var(--ink-2); font-size: .85rem; }
.scroll { overflow-x: auto; }

/* Nhãn */
.tag { display: inline-block; font-size: .8rem; padding: .05rem .5rem; border-radius: 999px; background: var(--violet-soft); color: var(--violet); font-weight: 600; white-space: nowrap; }
.tag.ok { background: var(--ok-soft); color: var(--ok); } .tag.bad { background: var(--bad-soft); color: var(--bad); } .tag.warn { background: var(--warn-soft); color: var(--warn); }
.diff { letter-spacing: 1px; color: var(--violet); }

/* Gợi ý bài: ba bài theo mục đích */
.recs { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1rem; }
.rec { border: 1px solid var(--rule); border-top: 4px solid var(--violet); border-radius: var(--r); padding: .9rem 1rem; background: var(--field); display: flex; flex-direction: column; }
.rec.luyen_lai { border-top-color: var(--bad); } .rec.ap_dung { border-top-color: var(--violet); } .rec.nang_cao { border-top-color: var(--ok); } .rec.ghim { border-top-color: var(--warn); }
.rec .why { color: var(--ink-2); font-size: .92rem; flex: 1; }
.rec .fb { margin-top: .6rem; display: flex; gap: .3rem; flex-wrap: wrap; }
.rec .fb button { font: inherit; font-size: .8rem; background: none; border: 1px solid var(--rule); border-radius: 999px; padding: .1rem .55rem; color: var(--ink-3); cursor: pointer; }
.rec .fb button:hover { border-color: var(--violet); color: var(--violet); }

/* Bản đồ kỹ năng trên nền ô ly — điểm nhấn thị giác duy nhất */
.olymap { background-color: var(--on-primary);
  background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 14px 14px; border: 1px solid var(--rule); border-radius: var(--r); padding: 1rem; }
.olymap .topic { margin-bottom: .8rem; }
.olymap .topic > span { display: inline-block; background: var(--field); padding: 0 .3rem; font-weight: 650; font-size: .9rem; }
.cells { display: flex; flex-wrap: wrap; gap: 6px; margin-top: .35rem; }
.cell { width: 168px; min-height: 56px; padding: .4rem .55rem; border: 1.5px solid var(--rule); background: var(--field); border-radius: 3px; font-size: .82rem; line-height: 1.35; }
.cell b { display: block; font-size: .72rem; font-weight: 600; color: var(--ink-3); margin-top: .15rem; }
.cell.dang_hoc { border-color: var(--violet-2); background: var(--violet-soft); }
.cell.thanh_thao { border-color: var(--violet); background: var(--violet); color: var(--on-primary); }
.cell.thanh_thao b { color: var(--on-primary-muted); }
.cell.untaught { border-style: dashed; color: var(--ink-3); background: transparent; }
.legend { display: flex; gap: 1rem; font-size: .8rem; color: var(--ink-3); margin-top: .5rem; flex-wrap: wrap; }
.legend i { display: inline-block; width: 12px; height: 12px; border: 1.5px solid var(--rule); vertical-align: -1px; margin-right: .3rem; }
.legend i.dang_hoc { background: var(--violet-soft); border-color: var(--violet-2); } .legend i.thanh_thao { background: var(--violet); border-color: var(--violet); }
.heat td.m { width: 26px; height: 26px; padding: 0; border: 2px solid var(--sheet); background: var(--grid); }
.heat td.m.dang_hoc { background: var(--heat-mid); } .heat td.m.thanh_thao { background: var(--violet); }
.heat th.sk { writing-mode: vertical-rl; transform: rotate(180deg); font-weight: 500; font-size: .75rem; height: 150px; padding: .3rem 0; }

/* Không gian làm bài */
.statement pre, pre.code { font: .88rem/1.5 var(--mono); background: var(--code-bg); border: 1px solid var(--rule); padding: .6rem .75rem; border-radius: var(--r); overflow-x: auto; white-space: pre; }
code { font-family: var(--mono); font-size: .9em; background: var(--code-bg); padding: 0 .25rem; border-radius: 3px; }
.editor { font: .9rem/1.55 var(--mono); min-height: 320px; tab-size: 4; white-space: pre; background: var(--editor-bg); }
.result .g { display: flex; justify-content: space-between; gap: .75rem; padding: .35rem 0; border-bottom: 1px dashed var(--rule); }
.result details { margin: .3rem 0 .5rem; }
.chat { max-height: 420px; overflow-y: auto; }
.msg { padding: .55rem .75rem; border-radius: var(--r); margin-bottom: .5rem; white-space: pre-wrap; }
.msg.student { background: var(--code-bg); margin-left: 15%; }
.msg.assistant { background: var(--violet-soft); border-left: 3px solid var(--violet); margin-right: 5%; }
.msg .lv { font-size: .76rem; font-weight: 700; color: var(--violet); display: block; margin-bottom: .15rem; }
.ladder { display: flex; gap: 4px; margin: .35rem 0 .6rem; }
.ladder span { flex: 1; height: 6px; border-radius: 3px; background: var(--grid); }
.ladder span.used { background: var(--violet); } .ladder span.locked { background: repeating-linear-gradient(45deg, var(--grid) 0 3px, var(--field) 3px 6px); }
details.ed { border: 1px solid var(--rule); border-radius: var(--r); padding: .5rem .75rem; margin-bottom: .5rem; background: var(--field); }
details.ed summary { cursor: pointer; font-weight: 600; }
details.ed.locked summary { cursor: default; color: var(--ink-3); }
.check-list li { margin-bottom: .35rem; }
.check-list .pass { color: var(--ok); } .check-list .fail { color: var(--bad); } .check-list .warn { color: var(--warn); }
.timeline li { margin-bottom: .2rem; }
.busy { opacity: .6; pointer-events: none; }
@media (prefers-reduced-motion: no-preference) { .btn, .nav a { transition: background .15s, color .15s, border-color .15s; } }

/* Bảng điểm */
table.grades th.asg { min-width: 92px; font-size: .8rem; vertical-align: bottom; }
table.grades td.gc { text-align: center; font-weight: 600; font-variant-numeric: tabular-nums; border-left: 1px solid var(--rule); }
table.grades td.gc a { color: inherit; text-decoration: none; display: block; }
.gc.ac { background: var(--ok-soft); color: var(--ok); }
.gc.partial, .gc.late { background: var(--warn-soft); color: var(--warn); }
.gc.zero, .gc.missing { background: var(--bad-soft); color: var(--bad); }
.gc.error { color: var(--bad); } .gc.none, .gc.pending { color: var(--ink-3); }
.legend i.gc { border: 0; }
.joincode { font: 700 1.35rem/1 var(--mono); letter-spacing: .18em; color: var(--violet); }

/* In phiếu tài khoản */
.printonly { display: none; }
@media print {
  .top, .noprint, .flash { display: none !important; }
  main { padding: 0; max-width: none; }
  body { background: #fff; }
  .printonly { display: grid; grid-template-columns: 1fr 1fr; gap: 0; }
  .slip { border: 1px dashed #999; padding: .7rem .9rem; break-inside: avoid; font-size: 11pt; line-height: 1.5; }
  .slip code { background: none; font-size: 12pt; font-weight: 700; }
}
table.grades td.gc { position: relative; }
table.grades td.gc sup { position: absolute; top: 3px; right: 5px; font-size: .62rem; }

/* Bộ lọc, thống kê, thao tác hàng loạt */
.fgrid { display: grid; grid-template-columns: repeat(auto-fill, minmax(170px, 1fr)); gap: .25rem .9rem; align-items: start; }
.fgrid .wide { grid-column: span 2; }
@media (max-width: 560px) { .fgrid .wide { grid-column: auto; } }
.filters label { margin-top: .2rem; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: .75rem; margin-bottom: 1.25rem; }
.panel .stats { margin-bottom: 0; }
.stat { background: var(--sheet); border: 1px solid var(--rule); border-radius: var(--r); padding: .7rem .9rem; font-size: .85rem; color: var(--ink-2); line-height: 1.35; }
.stat .n { display: block; font-size: 1.6rem; font-weight: 700; color: var(--violet); font-variant-numeric: tabular-nums; margin-bottom: .15rem; }
.meter { display: inline-block; width: 70px; height: 8px; background: var(--grid); border-radius: 4px; vertical-align: middle; overflow: hidden; }
.meter > span, .hb .bar > span { display: block; height: 100%; border-radius: 4px; }
.low { background: var(--bad); } .mid { background: var(--accent-warm); } .high { background: var(--ok); }
.hbars .hb { display: grid; grid-template-columns: 9rem 1fr 3rem; gap: .5rem; align-items: center; margin-bottom: .35rem; font-size: .88rem; }
.hb .bar { height: 12px; background: var(--grid); border-radius: 4px; overflow: hidden; }
.vbars { display: flex; align-items: flex-end; gap: 4px; height: 160px; padding-top: .5rem; }
.vb { flex: 1; display: flex; flex-direction: column; align-items: center; height: 100%; justify-content: flex-end; }
.vb .bar { width: 100%; max-width: 28px; background: var(--violet-soft); border: 1px solid var(--violet-2); border-radius: 3px 3px 0 0; display: flex; align-items: flex-end; min-height: 2px; }
.vb .bar .ac { display: block; width: 100%; background: var(--violet); }
.vb .d { font-size: .7rem; color: var(--ink-3); margin-top: .2rem; }
.bulkbar { border-top: 3px solid var(--violet); }
.tabs { display: flex; gap: .25rem; border-bottom: 1px solid var(--rule); margin-bottom: .75rem; flex-wrap: wrap; }
.tab { font: inherit; background: none; border: 0; border-bottom: 2px solid transparent; padding: .4rem .8rem; color: var(--ink-2); cursor: pointer; margin-bottom: -1px; }
.tab.on { color: var(--violet); border-bottom-color: var(--violet); font-weight: 600; }
.pager { display: flex; gap: .3rem; margin-top: 1rem; flex-wrap: wrap; align-items: center; }
.pager a, .pager .cur { min-width: 2rem; text-align: center; padding: .2rem .5rem; border: 1px solid var(--rule); border-radius: var(--r); text-decoration: none; }
.pager .cur { background: var(--violet); color: var(--on-primary); border-color: var(--violet); }
.pager .gap { color: var(--ink-3); }
input[type=search] { font: inherit; width: 100%; padding: .45rem .6rem; border: 1px solid var(--rule); border-radius: var(--r); background: var(--field); color: var(--ink); }

/* Xem mã */
.btn.sm { padding: .15rem .55rem; font-size: .82rem; font-weight: 500; }
.codebox { border: 1px solid var(--rule); border-radius: var(--r); overflow: hidden; background: var(--codebox-bg); }
.codebar { display: flex; justify-content: space-between; align-items: center; gap: .5rem; padding: .3rem .6rem; background: var(--code-bar); border-bottom: 1px solid var(--rule); font-size: .8rem; color: var(--ink-2); }
.codebox pre.code { border: 0; border-radius: 0; margin: 0; max-height: 560px; overflow: auto; }
pre.num { counter-reset: ln; padding-left: 0; }
pre.num .ln { counter-increment: ln; display: block; padding-left: 3.4em; position: relative; min-height: 1.5em; }
pre.num .ln::before { content: counter(ln); position: absolute; left: 0; width: 2.6em; text-align: right; color: var(--ink-3); user-select: none; }
pre.num .ln:hover { background: var(--hl); }
table.diff { font: .86rem/1.45 var(--mono); border-collapse: collapse; }
table.diff td { border: 0; padding: 0 .4rem; vertical-align: top; }
table.diff td.n { color: var(--ink-3); text-align: right; width: 3em; user-select: none; }
table.diff td.op { width: 1.2em; font-weight: 700; user-select: none; }
table.diff pre { margin: 0; font: inherit; white-space: pre; }
table.diff tr.add { background: var(--add-bg); } table.diff tr.add td.op { color: var(--ok); }
table.diff tr.del { background: var(--del-bg); } table.diff tr.del td.op { color: var(--bad); }
tr.cur td { background: var(--violet-soft); }
details.cc > summary { cursor: pointer; list-style: none; }
details.cc > summary::-webkit-details-marker { display: none; }
details.cc[open] > summary { padding-bottom: .5rem; border-bottom: 1px solid var(--rule); }

/* Giải thích lỗi */
.explain { background: var(--explain-bg); border-left: 4px solid var(--accent-warm); padding: .5rem .75rem; margin: .4rem 0; border-radius: 0 var(--r) var(--r) 0; font-size: .92rem; }
.explain strong { display: block; color: var(--warn); margin-bottom: .1rem; }

/* Hành trình của em */
.jgrid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.jbox { border: 1px solid var(--rule); border-radius: var(--r); padding: .8rem 1rem; display: flex; flex-direction: column; gap: .25rem; }
.jbox .big { font-size: 2.2rem; font-weight: 700; line-height: 1; color: var(--violet); font-variant-numeric: tabular-nums; }
.jbox .big small { font-size: 1rem; color: var(--ink-3); font-weight: 600; }
.strip { display: flex; gap: 4px; margin: .35rem 0; }
.strip i { width: 22px; height: 22px; border-radius: 3px; background: var(--grid); }
.strip i.on { background: var(--violet); }
.meter.wide { width: 100%; height: 10px; margin-top: .3rem; }
.badges { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: .5rem; }
.badge { display: flex; gap: .6rem; align-items: flex-start; padding: .5rem .65rem; border: 1px dashed var(--rule); border-radius: var(--r); color: var(--ink-3); }
.badge strong { display: block; font-size: .9rem; }
.badge .small { display: block; line-height: 1.35; }
.badge .bmark { flex: none; width: 26px; height: 26px; border-radius: 50%; border: 2px solid var(--rule); margin-top: .1rem; }
.badge.on { border-style: solid; border-color: var(--violet-2); background: var(--violet-soft); color: var(--ink); }
.badge.on .bmark { border-color: var(--violet); background: radial-gradient(circle, var(--field) 0 28%, var(--violet) 30%); }
.coach { border-top: 3px solid var(--ok); }
.report p { max-width: 80ch; }

/* ===================================================================
   Chủ đề màu. Mặc định: Mực tím. Người dùng chọn trong "Giao diện".
   Mỗi chủ đề chỉ gán lại biến màu, bố cục giữ nguyên.
   =================================================================== */
.top { border-top: 4px solid transparent; border-image: linear-gradient(90deg, var(--violet), var(--accent-2), var(--ok)) 1; }

[data-theme="bien-xanh"] { --violet: #0B5F8A; --violet-2: #1683B8; --violet-soft: #E3F1F8; --heat-mid: #9CCBE3; --hl: #DCEEF8;
  --on-primary-muted: #CFE7F5; --accent-2: #13A3A8; --paper: #F3F7FA; }
[data-theme="la-non"] { --violet: #1E6B52; --violet-2: #2A8C6B; --violet-soft: #E2F3EC; --heat-mid: #9FD3BE; --hl: #DDF0E8;
  --on-primary-muted: #CDEBDF; --accent-2: #8DB42A; --paper: #F4F8F5; }
[data-theme="hoang-hon"] { --violet: #B4461A; --violet-2: #D1622F; --violet-soft: #FCEBE3; --heat-mid: #F0B99E; --hl: #FBE3D7;
  --on-primary-muted: #F8D5C4; --accent-2: #E0A326; --paper: #FBF7F4; }
[data-theme="hoa-sen"] { --violet: #A6246B; --violet-2: #C23D86; --violet-soft: #F9E6F0; --heat-mid: #E7A9CA; --hl: #F6DDEA;
  --on-primary-muted: #F2CFE2; --accent-2: #7B4FC9; --paper: #FAF6F8; }
[data-theme="cau-vong"] { --violet: #3D4ED8; --violet-2: #5B6BF0; --violet-soft: #E8EAFD; --heat-mid: #AEB6F5; --hl: #E3E6FC;
  --on-primary-muted: #D5DAFB; --accent-2: #E4478A; --paper: #F6F7FD; }
[data-theme="cau-vong"] .top { border-top-width: 6px; border-image: linear-gradient(90deg, #E5484D, #F76B15, #FFB224, #30A46C, #0091FF, #6E56CF, #D6409F) 1; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+1) .cell.thanh_thao { background: #E5484D; border-color: #E5484D; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+2) .cell.thanh_thao { background: #D9570F; border-color: #D9570F; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+3) .cell.thanh_thao { background: #2F8C5E; border-color: #2F8C5E; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+4) .cell.thanh_thao { background: #0073CC; border-color: #0073CC; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+5) .cell.thanh_thao { background: #6E56CF; border-color: #6E56CF; }
[data-theme="cau-vong"] .olymap .topic:nth-child(6n+6) .cell.thanh_thao { background: #C2378D; border-color: #C2378D; }
[data-theme="cau-vong"] .badge.on:nth-child(3n+1) .bmark { background: radial-gradient(circle, var(--field) 0 28%, #E5484D 30%); border-color: #E5484D; }
[data-theme="cau-vong"] .badge.on:nth-child(3n+2) .bmark { background: radial-gradient(circle, var(--field) 0 28%, #30A46C 30%); border-color: #30A46C; }
[data-theme="cau-vong"] .badge.on:nth-child(3n+3) .bmark { background: radial-gradient(circle, var(--field) 0 28%, #0091FF 30%); border-color: #0091FF; }

/* Nền tối: dịu mắt khi làm bài buổi tối, đủ tương phản để đọc mã */
[data-theme="dem"] {
  --paper: #13151B; --sheet: #1B1E26; --ink: #E7E9F0; --ink-2: #B9BECC; --ink-3: #8C92A4; --rule: #2E3340; --grid: #262B36;
  --violet: #A78BFA; --violet-2: #C4B5FD; --violet-soft: #2A2442; --on-primary: #15121F; --on-primary-muted: #3B2F63;
  --ok: #4ADE80; --ok-soft: #14301E; --warn: #F5B454; --warn-soft: #3A2C12; --bad: #F87171; --bad-soft: #3B1A1A;
  --field: #232733; --editor-bg: #181B23; --code-bg: #161922; --code-bar: #20242F; --codebox-bg: #161922; --hl: #2A2442;
  --heat-mid: #5B4A99; --explain-bg: #33280F; --accent-warm: #F5B454; --add-bg: #14301E; --del-bg: #3B1A1A; --accent-2: #F5B454;
  color-scheme: dark;
}
[data-theme="dem"] .olymap { background-image: linear-gradient(#232733 1px, transparent 1px), linear-gradient(90deg, #232733 1px, transparent 1px); }
[data-theme="dem"] .cell.thanh_thao b { color: var(--on-primary-muted); }

/* Trang chọn giao diện */
.themes { display: grid; grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); gap: .75rem; }
.theme-card { display: block; border: 2px solid var(--rule); border-radius: 10px; padding: .7rem; cursor: pointer; background: var(--sheet); }
.theme-card:has(input:checked) { border-color: var(--violet); box-shadow: 0 0 0 3px var(--violet-soft); }
.theme-card input { position: absolute; opacity: 0; }
.theme-card .sw { display: flex; height: 38px; border-radius: 6px; overflow: hidden; margin-bottom: .5rem; border: 1px solid rgba(0,0,0,.08); }
.theme-card .sw span { flex: 1; }
.theme-card strong { display: block; }
details.inline-edit > summary { list-style: none; display: inline-block; }
details.inline-edit > summary::-webkit-details-marker { display: none; }
details.inline-edit[open] { background: var(--codebox-bg); border: 1px solid var(--rule); border-radius: var(--r); padding: .5rem; margin: .25rem 0; }

/* ================= Trình soạn mã IDE ================= */
:root { --tk-kw: #8A2BB2; --tk-bi: #0B6BA8; --tk-str: #A34A00; --tk-num: #0E7A55; --tk-com: #7A8296; --tk-fn: #1D4ED8; --tk-pre: #B42318;
        --ide-cur: rgba(75, 46, 131, .06); --ide-err: rgba(180, 35, 24, .14); --ide-sel: rgba(75, 46, 131, .25); }
[data-theme="dem"] { --tk-kw: #D29BFF; --tk-bi: #6CC4FF; --tk-str: #F5B454; --tk-num: #7EE2A8; --tk-com: #7D8498; --tk-fn: #93B4FF; --tk-pre: #FF8A80;
        --ide-cur: rgba(167, 139, 250, .08); --ide-err: rgba(248, 113, 113, .18); --ide-sel: rgba(167, 139, 250, .35); }
.ide { --ide-fs: 14px; border: 1px solid var(--rule); border-radius: var(--r); background: var(--editor-bg); overflow: hidden; display: flex; flex-direction: column; }
.ide-bar { display: flex; justify-content: space-between; align-items: center; gap: .5rem; padding: .25rem .5rem; background: var(--code-bar); border-bottom: 1px solid var(--rule); font-size: .8rem; color: var(--ink-2); }
.ide-tools { display: flex; gap: .25rem; flex-wrap: wrap; }
.ide-tools button { font: inherit; font-size: .78rem; background: var(--field); color: var(--ink-2); border: 1px solid var(--rule); border-radius: 4px; padding: .1rem .5rem; cursor: pointer; }
.ide-tools button:hover { border-color: var(--violet); color: var(--violet); }
.ide-help { font-size: .8rem; padding: .4rem .6rem; background: var(--violet-soft); border-bottom: 1px solid var(--rule); line-height: 1.7; }
.ide-scroll { position: relative; overflow: auto; height: 380px; min-height: 160px; resize: vertical; }
.ide-inner { display: flex; min-height: 100%; min-width: 100%; width: max-content; }
.ide-gutter, .ide-hl, .ide-input { font: var(--ide-fs)/1.5 var(--mono); tab-size: 4; letter-spacing: 0; padding: .5rem .6rem; margin: 0; border: 0; white-space: pre; }
.ide-gutter { position: sticky; left: 0; z-index: 3; text-align: right; color: var(--ink-3); background: var(--code-bar); border-right: 1px solid var(--rule); user-select: none; min-width: 3.2em; }
.ide-code { position: relative; flex: 1; min-width: 0; }
.ide-hl { position: relative; z-index: 1; pointer-events: none; color: var(--ink); background: none; overflow: visible; min-height: 100%; }
.ide-input { position: absolute; inset: 0; z-index: 2; width: 100%; height: 100%; resize: none; overflow: hidden; background: transparent; color: transparent;
  caret-color: var(--ink); outline: none; box-shadow: none; }
.ide-input::selection { background: var(--ide-sel); color: transparent; }
.ide:focus-within { border-color: var(--violet-2); box-shadow: 0 0 0 2px var(--violet-soft); }
.ide-curline, .ide-errline { position: absolute; left: 0; right: 0; z-index: 0; pointer-events: none; }
.ide-curline { background: var(--ide-cur); }
.ide-errline { background: var(--ide-err); border-left: 3px solid var(--bad); }
.ide-full { position: fixed; inset: 0; z-index: 1000; border-radius: 0; }
.ide-full .ide-scroll { height: auto; flex: 1; resize: none; }
body.ide-noscroll { overflow: hidden; }
.tk-kw { color: var(--tk-kw); font-weight: 600; } .tk-bi { color: var(--tk-bi); } .tk-str { color: var(--tk-str); } .tk-num { color: var(--tk-num); }
.tk-com { color: var(--tk-com); font-style: italic; } .tk-fn { color: var(--tk-fn); } .tk-pre { color: var(--tk-pre); }
.explain a[data-goto] { font-weight: 600; margin-left: .25rem; }
.ide-hl code { background: none; padding: 0; border-radius: 0; font: inherit; color: inherit; }

/* Bài học */
.lesson-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: .75rem; }
.lesson-card { display: flex; flex-direction: column; gap: .35rem; padding: .8rem .9rem; border: 1px solid var(--rule); border-left: 4px solid var(--violet); border-radius: var(--r); text-decoration: none; color: var(--ink); background: var(--field); }
.lesson-card:hover { border-color: var(--violet); }
.lesson-card.read { border-left-color: var(--ok); }
.lesson-split { grid-template-columns: minmax(0, 7fr) minmax(0, 4fr); }
.lesson-body h2 { font-size: 1.2rem; margin-top: 1.4rem; padding-bottom: .25rem; border-bottom: 2px solid var(--violet-soft); }
.lesson-body h3 { font-size: 1.05rem; }
.lesson-body ul, .lesson-body ol { margin: 0 0 .8rem; padding-left: 1.4rem; max-width: 72ch; }
.lesson-body li { margin-bottom: .25rem; }
.lesson-body .lead { font-size: 1.05rem; color: var(--ink-2); }
.runner { margin: .5rem 0 1rem; }
.runner .rout { margin-top: .5rem; }
fieldset.q { border: 1px solid var(--rule); border-radius: var(--r); padding: .6rem .8rem; margin: 0 0 .75rem; }
fieldset.q legend { font-weight: 600; padding: 0 .25rem; }
fieldset.q legend p, .opt p { display: inline; margin: 0; }
.opt { display: flex; gap: .5rem; align-items: flex-start; font-weight: 400; margin: .3rem 0; cursor: pointer; }
.opt input { margin-top: .35rem; }
fieldset.q.right { border-color: var(--ok); background: var(--ok-soft); }
fieldset.q.wrong { border-color: var(--bad); background: var(--bad-soft); }
.opt.correct span { font-weight: 700; color: var(--ok); }
.q-fb { font-size: .9rem; margin-top: .35rem; }
ul.plain { list-style: none; padding: 0; margin: 0; } ul.plain li { padding: .3rem 0; border-bottom: 1px dashed var(--rule); }
@media (max-width: 900px) { .lesson-split { grid-template-columns: 1fr; } }
/* Trình soạn nằm trong nội dung bài học/đề bài: không để kiểu "pre" của nội dung đè lên, tránh lệch con trỏ */
.ide .ide-gutter, .ide .ide-hl, .ide .ide-input { font: var(--ide-fs)/1.5 var(--mono); padding: .5rem .6rem; margin: 0; border: 0; border-radius: 0;
  white-space: pre; overflow: visible; max-height: none; }
.ide .ide-hl { background: none; }
.ide .ide-gutter { background: var(--code-bar); border-right: 1px solid var(--rule); }
.ide .ide-input { overflow: hidden; background: transparent; }

/* Biểu trưng CTOJ Tutor: đổi màu theo giao diện */
.logo { flex: none; display: block; }
.logo .logo-bg { fill: var(--violet); }
.logo .logo-fg { stroke: var(--on-primary); }
.logo .logo-fgf { fill: var(--on-primary); }
.logo .logo-star { fill: #FFB224; }
.brand { gap: .55rem; }
.brand .mark { display: none; }
.bname { font-weight: 800; letter-spacing: .01em; color: var(--ink); font-size: 1.12rem; }
.login-brand { display: flex; align-items: center; justify-content: center; gap: .9rem; margin-top: 7vh; }
.login-brand .lb-name { font-size: 2rem; font-weight: 800; line-height: 1.1; color: var(--ink); letter-spacing: .01em; }
.login-brand .lb-tag { color: var(--ink-2); font-size: 1rem; }
.bname .accent, .lb-name .accent { color: var(--violet); }

/* Màu thương hiệu CTOJ Tutor: logo giữ cố định xanh lá (đồng bộ với MathX), không đổi theo giao diện */
:root { --brand-green: #1FB54B; --brand-green-text: #169A3E; --brand-blue: #1F63B8; }
[data-theme="dem"] { --brand-green-text: #3FD06A; --brand-blue: #6FA3F0; }
.logo .logo-bg { fill: var(--brand-green); }
.logo .logo-fg { stroke: #FFFFFF; }
.logo .logo-fgf { fill: #FFFFFF; }
.logo .logo-star { fill: var(--brand-blue); }
.bname .accent, .lb-name .accent { color: var(--brand-green-text); }
/* Bộ màu thương hiệu: xanh lá CTOJ, điểm nhấn xanh dương (đồng bộ logo) */
[data-theme="ctoj"] { --violet: #15803D; --violet-2: #1FA24C; --violet-soft: #E3F6E8; --heat-mid: #9FDDB0; --hl: #DDF3E3;
  --on-primary-muted: #CBEFD5; --accent-2: #1F63B8; --paper: #F4F9F5; --ide-cur: rgba(21, 128, 61, .06); --ide-sel: rgba(21, 128, 61, .22); }

/* Theo dõi lớp, xem lại quá trình */
.dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; background: var(--grid); vertical-align: 0; }
.dot.online { background: var(--ok); box-shadow: 0 0 0 3px var(--ok-soft); }
.dot.away { background: var(--accent-warm); }
.dot.never { background: transparent; border: 1.5px dashed var(--ink-3); }
table.monitor tr.st-online td:first-child { font-weight: 600; }
a.tab { text-decoration: none; display: inline-block; }
.rp-events { list-style: none; padding: 0; margin: 0; max-height: 560px; overflow-y: auto; }
.rp-events li { padding: .35rem 0 .35rem .6rem; border-left: 3px solid var(--rule); margin-left: .2rem; font-size: .9rem; }
.rp-events li.submit { border-left-color: var(--violet); } .rp-events li.run { border-left-color: var(--ink-3); }
.rp-events li.paste { border-left-color: var(--warn); } .rp-events li.ev { border-left-color: var(--grid); color: var(--ink-2); }
.rp-events a.cur { font-weight: 700; }
pre.num .ln.d-add { background: var(--add-bg); } pre.num .ln.d-del { background: var(--del-bg); text-decoration: line-through; color: var(--ink-3); }

/* ===== v12: menu nhóm, chuông, kỳ thi, đọc mã, lộ trình ===== */
.navgroup { position: relative; }
.navgroup > summary { list-style: none; cursor: pointer; color: var(--ink-2); padding: .2rem 0; border-bottom: 2px solid transparent; }
.navgroup > summary::-webkit-details-marker { display: none; }
.navgroup > summary::after { content: " ▾"; font-size: .75em; }
.navgroup > summary.on, .navgroup > summary:hover { color: var(--violet); border-bottom-color: var(--violet); }
.navmenu { position: absolute; top: calc(100% + .45rem); left: -.6rem; z-index: 50; min-width: 13rem; background: var(--sheet); border: 1px solid var(--rule);
  border-radius: var(--r); box-shadow: 0 8px 24px rgba(0,0,0,.12); padding: .35rem; display: flex; flex-direction: column; }
.navmenu a { padding: .4rem .6rem; border-radius: 4px; border: 0 !important; color: var(--ink); text-decoration: none; }
.navmenu a:hover, .navmenu a.on { background: var(--violet-soft); color: var(--violet); }
.bell { position: relative; margin-left: auto; color: var(--ink-2); display: inline-flex; padding: .2rem; }
.bell:hover { color: var(--violet); }
.bell + .who { margin-left: .5rem; }
.badge-n { position: absolute; top: -4px; right: -8px; background: var(--bad); color: #fff; font-size: .68rem; font-weight: 700; border-radius: 999px; padding: 0 .35rem; line-height: 1.35; }
ul.notif { list-style: none; margin: 0; padding: 0; } ul.notif li { padding: .55rem .4rem; border-bottom: 1px solid var(--rule); display: flex; justify-content: space-between; gap: 1rem; }
ul.notif li.new { background: var(--violet-soft); font-weight: 600; }
.contest-bar { display: flex; gap: 1rem; align-items: center; flex-wrap: wrap; padding: .55rem .9rem; margin: -.5rem 0 1rem; border-radius: var(--r); background: var(--violet-soft); border: 1px solid var(--rule); }
.contest-bar.live { background: var(--warn-soft); border-color: var(--warn); }
.countdown { font-variant-numeric: tabular-nums; font-size: 1.05em; } .countdown.urgent { color: var(--bad); }
.countdown-big { font-size: 1.3rem; }
table.scoreboard th.pc, table.scoreboard td.pc { text-align: center; min-width: 3.4rem; border-left: 1px solid var(--rule); }
table.scoreboard td.ac { background: var(--ok-soft); color: var(--ok); font-weight: 700; }
table.scoreboard td.wa { background: var(--bad-soft); color: var(--bad); }
table.scoreboard td.pend { background: var(--warn-soft); color: var(--warn); }
table.scoreboard tr.me td { outline: 2px solid var(--violet); outline-offset: -2px; }
.pz-list { list-style: none; margin: 0; padding: .4rem; min-height: 180px; border: 2px dashed var(--rule); border-radius: var(--r); background: var(--codebox-bg); }
ol.pz-dst { counter-reset: pz; } ol.pz-dst li.pz::before { counter-increment: pz; content: counter(pz); color: var(--ink-3); font-size: .75rem; min-width: 1.4rem; }
.pz-list.over { border-color: var(--violet); background: var(--violet-soft); }
li.pz { display: flex; align-items: center; gap: .4rem; background: var(--field); border: 1px solid var(--rule); border-radius: 4px; padding: .3rem .4rem; margin-bottom: .3rem; cursor: grab; }
li.pz.bad { border-color: var(--bad); background: var(--bad-soft); }
.pz-code { flex: 1; font: .9rem/1.45 var(--mono); background: none; padding: 0; white-space: pre; overflow-x: auto; }
.pz-btns { display: flex; gap: .2rem; } .pz-btns button { font: inherit; font-size: .8rem; border: 1px solid var(--rule); background: var(--sheet); color: var(--ink-2); border-radius: 4px; cursor: pointer; padding: .05rem .4rem; }
pre.blank-code { white-space: pre; line-height: 2.1; }
input.blank { font: inherit; width: auto; min-width: 3ch; padding: .05rem .3rem; border: 1.5px solid var(--violet-2); border-radius: 4px; background: var(--field); color: var(--ink); }
input.blank.ok { border-color: var(--ok); background: var(--ok-soft); } input.blank.bad { border-color: var(--bad); background: var(--bad-soft); }
ol.path-steps { list-style: none; margin: .8rem 0 0; padding: 0; }
ol.path-steps li { position: relative; padding: .5rem 0 .5rem 1.8rem; border-left: 2px solid var(--rule); margin-left: .5rem; }
ol.path-steps .ps-dot { position: absolute; left: -.5rem; top: .75rem; width: 14px; height: 14px; border-radius: 50%; background: var(--sheet); border: 2px solid var(--rule); }
ol.path-steps li.ps-done { border-left-color: var(--ok); } ol.path-steps li.ps-done .ps-dot { background: var(--ok); border-color: var(--ok); }
ol.path-steps li.ps-current .ps-dot { border-color: var(--violet); background: var(--violet-soft); box-shadow: 0 0 0 4px var(--violet-soft); }
ol.path-steps.edit li { padding-left: 1rem; display: flex; justify-content: space-between; gap: .5rem; align-items: center; flex-wrap: wrap; }
.ask-teacher > summary { cursor: pointer; }